Networks And Communication Part D

Bandwidth
1. This is the measure of how much data can be transferred in a time
2. The higher the bandwidth the more data that can be transferred
3. Often measured in Mbps which is bits per second or Mpbs which is bytes per second
4. The more frequencies available on a channel the faster it is
Bottleneck
1. A bottleneck is the smallest bandwidth that exists between the user and the place that data is being downloaded from
2. The data even though it may have been travelling more quickly before will get slowed down at the bottle neck
Cables
1. Copper Cable
  1. Modern copper cables are in twisted pairs, this is narrow wire that is insulated and twisted in twos, without an earth wire- known as a UTP or Ethernet cables, this can sometimes result in loss of data.
  2. There are also STP cables, these do have an earth which is a metal shield that reduces electromagnetic interference, these have a higher bandwidth capability so are used in high speed networks
  3. Coaxial cables which were used in older networks and is still used in the television industry as it has a capacity for high bandwidth. This has two wires and the outer cable acts as a shield to electromagnetic interference.
2. Optical Cable
  1. Fibre-optic cables use small glass tubes to reflect light along the tube
  2. These have much higher bandwidth as they do not have any electrical interference
3. Wireless
  1. These can be radio, satellite and infra-red.
  2. This has a lower bandwidth than the wired methods
  3. Can be interrupted by physical obstacles such as walls
Importance of bandwidth
1. The importance of bandwidth depends on what it is being used for
2. If something is being streamed then a large bandwidth is needed
3. If something is being downloaded overnight then it does not matter too much as it is going to be used the next morning or day
4. Live/real time data needs a high bandwidth as if it does not then it will freeze and not work well

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Networks And Communication Part D

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